La Trobe University
CSE1PE: Programming Environment
Understanding the Program Development Steps
In CSE1PE, the following steps are very efficiently and proactively used so it’s
important to read the following and pay close attention to each detail.
Step 1: Define the Problem
In order to continue on with a program development, you need a clear vision and to
understand what is going to happen with your program. This takes the form of a
‘visual representation’. Basically, it’s a diagram which represents the flow of
processing from the input, to the output.
Figure 1.1: A sample visual diagram of a basic shop purchase.
Output:
Inputs: Change is calculated by
deducting the price of
price price
cash the item (price) from cash
the cash supplied. change
In the left box, we have our inputs. If we go into a shop to purchase an item. We have
two things that we need to assume. The price of the item, and the cash we will give to
the attendant. We know this, but we want to know the change that we receive.
The middle circle is the processing section. We explain in simple English what’s
going on in the background. For this example, we simply write a sentence explaining
how the change is calculated, which is deducting the price of the item from the
cash amount.
Of course, depending on the problem description, it’s essential we output the
change. You may or may not need to output the cash and price again, but I’ve done
that also for the example.
Written by Aaron Brown
La Trobe University (2013) Step 2: Specify a high level solution
You cannot now just develop a solution that has complex features with it. We use a
defining diagram to do rigorous planning to ensure that when it comes time to
programming the program, we are fully prepared.
A defining diagram simply lists the Inputs, Processes and Outputs in a table-
like format. In some way this is translating the diagram above, into a more complex
and systematic approach.
Figure 2.1: A sample defining diagram of the ‘shop’ example.
INPUTS PROCESSES OUTPUTS
price Change = cash - price price
cash cash
change
 Inputs: Are the things that we know we have to enter to calculate the change.
Without one or both of these, we cannot calculate. The inputs (price and cash)
seen above are called variables. Variables need to have a unique but
justified name which is relevant.
 Processes: Is the ‘back end’ processing that is required to calculate the
desired output (which is to display the change). So therefore, we write the
calculation to do this, which is “Change = cash – price”.
 Outputs: Are the ‘final products’ for the user to see at the end.
If you have done an IPO chart before, this is somewhat similar with a few
modifications to it.
Step 3: Outline the Solution
If there is additional information which needs to be added, this section is where you
add it. If you have functions, if/else statements or anything that has not been
justified, justify it in this section. Pretend that there is someone that has never seen
or used your program before, and needs to know details about it. This is where you
provide these details (if applicable).
Step 4: Develop the outline into algorithm
To do this step, we use what’s called Pseudocode and a Data Dictionary.
Pseudocode is a series of logical steps that is performed for the program to be
executed successfully.
Written by Aaron Brown
La Trobe University (2013) Figure 4.1: A sample Pseudocode with explanations for the ‘shop’ example.
Always start with the ‘idea’ or ‘goal’
calculateChange() as the ‘function’. It has a name then
() after it.
1. START
2. INPUT price The Pseudocode always starts with the
word ‘START’ in capitals. Each line of
3. INPUT cash the Pseudocode must be numbered.
4. change = cash – price
5. DISPLAY change
We must think about how the
6. STOP program will run. First, we would
need to ask for the item cost and
the price. We start each on a new
After the inputs have been given, line, with capital INPUT, a space,
we now need to calculate. This is then the variable name which we
the processing stage where we now have specified in the Defining
need to calculate for the output. Diagram (Step 2 (click)).
After all processing and inputs
have been collected, we now
DISPLAY the output of ‘change’.
To display or output the result, After everything has been done, to indicate
that the Pseudocode has finished, we type in
we type in capitals DISPLAY then capitals, STOP. This indicates the end of the
the variable (which we’ve given Pseudocode.
as ‘change’).